Method for estimating mobility state of UE and device supporting the same

ABSTRACT

Provided are a method of estimating mobility state of an UE and a device supporting the method. According to one embodiment of the present invention, the method includes: entering a second cell from a first cell, wherein the first cell provides specific information; receiving neighbor cell list from the second cell; and counting a number of cell changes for mobility state, based on whether the neighbor cell list from the second cell includes at least one of neighbor cells providing the specific information.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119 (e), this application claims the benefit ofearlier filing date and right of priority to Korean Patent ApplicationNo. 10-2018-0039993, filed on Apr. 5, 2018, the contents of which arehereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a wireless communication system, andmore particularly, to a method for estimating mobility state of UE and adevice supporting the same.

Related Art

Efforts have been made to develop an improved 5^(th)-generation (5G)communication system or a pre-5G communication system in order tosatisfy a growing demand on radio data traffic after commercializationof a 4^(th)-generation (4G) communication system. A standardization actfor a 5G mobile communication standard work has been formally started in3GPP, and there is ongoing discussion in a standardization working groupunder a tentative name of a new radio access (NR).

Meanwhile, an upper layer protocol defines a protocol state toconsistently manage an operational state of a user equipment (UE), andindicates a function and procedure of the UE in detail. In thediscussion on the NR standardization, an RRC state is discussed suchthat an RRC_CONNECTED state and an RRC_IDLE state are basically defined,and an RRC_INACTIVE state is additionally introduced.

Meanwhile, In the LTE network, mobility state of a UE is determined bynumber of cell reselections during recent time period. That is, the UEmay determine its mobility state only based on the number of cellreselection. As the UE performs mobility state estimation frequently ina certain time period, the UE determines itself as being in highermobility state. So the UE cannot realize its own mobility as far as cellreselection is not occurred even though it is moving fast.

In order to ensure high quality of user experience in high speed train,we have already exploited dedicated resource or specific design for thecoverage of high speed railway, which is normally called“High-speed-railway dedicated LTE network”. The so-called“High-speed-railway dedicated network (HSDN)” is different from thenetwork deployed for normal ground users or low-medium mobility usersthat is normally called “public LTE network”.

SUMMARY OF THE INVENTION

According to a prior art, during the UE on the train stays at the trainstation, the UE would not frequently reselect to other cells, so themobility state of the UE may be considered as medium or normal speed.

According to an embodiment of the present invention, a method for a userequipment (UE) in wireless communication system is provided. The methodmay comprise: entering a second cell from a first cell, wherein thefirst cell provides specific information; receiving neighbor cell listfrom the second cell; and counting a number of cell changes for mobilitystate, based on whether the neighbor cell list from the second cellincludes at least one of neighbor cells which provides the specificinformation.

The specific information may inform that a cell providing the specificinformation is high-speed-railway dedicated network (HSDN) cell.

The HSDN cell may include plurality of public cells.

The second cell may be a public cell.

The counting the number of cell changes for mobility state may include:increasing the counting until that the mobility state of the UE isconsidered as high mobility state when the neighbor cell list from thesecond cell includes the at least one of neighbor cells providing thespecific information.

The method may further comprise: entering a third cell from the secondcell; receiving neighbor cell list from the third cell; decreasing thecounting until that the mobility state of the UE is considered as normalmobility state when the neighbor cell list from the third cell does notinclude the at least one of neighbor cells providing the specificinformation.

The counting the number of cell changes for mobility state may include:counting cell change from the first cell to the second cell when theneighbor cell list from the second cell does not include the at leastone of neighbor cells providing the specific information.

The method may further comprise: adjusting priority on the first cell asa highest priority when the neighbor cell list includes the at least oneof neighbor cells providing the specific information.

The method may further comprise: adjusting priority on the first cell asa lowest priority when the neighbor cell list does not include the atleast one of neighbor cells providing the specific information.

According to another embodiment of the present invention, a userequipment (UE) in a wireless communication system is provided. The UEmay comprise: a transceiver for transmitting or receiving a radiosignal; and a processor coupled to the transceiver, the processorconfigured to: enter a second cell from a first cell, wherein the firstcell provides specific information; receive neighbor cell list from thesecond cell; and count a number of cell changes for mobility state,based on whether the neighbor cell list from the second cell includes atleast one of neighbor cells which provides the specific information.

The specific information may inform that a cell providing the specificinformation is high-speed-railway dedicated network (HSDN) cell.

The HSDN cell may include plurality of public cells.

The second cell may be a public cell.

The counting the number of cell changes for mobility state may include:increasing the counting until that the mobility state of the UE isconsidered as high mobility state when the neighbor cell list includesthe at least one of neighbor cells providing the specific information.

According to another embodiment of the present invention, a processorfor a wireless communication device in a wireless communication systemis provided. The processor may be configured to control the wirelesscommunication device to: enter a second cell from a first cell, whereinthe first cell provides specific information; receive neighbor cell listfrom the second cell; and count a number of cell changes for mobilitystate, based on whether the neighbor cell list from the second cellincludes at least one of neighbor cells which provides the specificinformation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a wireless communication system to whichtechnical features of the present invention can be applied.

FIG. 2 shows another example of a wireless communication system to whichtechnical features of the present invention can be applied.

FIG. 3 shows a block diagram of a user plane protocol stack to whichtechnical features of the present invention can be applied.

FIG. 4 shows a block diagram of a control plane protocol stack to whichtechnical features of the present invention can be applied.

FIG. 5 shows an example of overlapped coverage between dedicated networkand public network.

FIG. 6 shows a method for estimating mobility state of a UE according toan embodiment of the present invention.

FIG. 7 shows a method for estimating mobility state of a UE according toan embodiment of the present invention.

FIG. 8 shows an example of estimating mobility state of a UE accordingto an embodiment of the present invention.

FIG. 9 shows a UE to implement an embodiment of the present invention.

FIG. 10 shows more detailed UE to implement an embodiment of the presentinvention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The technical features described below may be used by a communicationstandard by the 3rd generation partnership project (3GPP)standardization organization, a communication standard by the instituteof electrical and electronics engineers (IEEE), etc. For example, thecommunication standards by the 3GPP standardization organization includelong-term evolution (LTE) and/or evolution of LTE systems. The evolutionof LTE systems includes LTE-advanced (LTE-A), LTE-A Pro, and/or 5G newradio (NR). The communication standard by the IEEE standardizationorganization includes a wireless local area network (WLAN) system suchas IEEE 802.11a/b/g/n/ac/ax. The above system uses various multipleaccess technologies such as orthogonal frequency division multipleaccess (OFDMA) and/or single carrier frequency division multiple access(SC-FDMA) for downlink (DL) and/or uplink (DL). For example, only OFDMAmay be used for DL and only SC-FDMA may be used for UL. Alternatively,OFDMA and SC-FDMA may be used for DL and/or UL.

FIG. 1 shows an example of a wireless communication system to whichtechnical features of the present invention can be applied.Specifically, FIG. 1 shows a system architecture based on anevolved-UMTS terrestrial radio access network (E-UTRAN). Theaforementioned LTE is a part of an evolved-UTMS (e-UMTS) using theE-UTRAN.

Referring to FIG. 1, the wireless communication system includes one ormore user equipment (UE; 10), an E-UTRAN and an evolved packet core(EPC). The UE 10 refers to a communication equipment carried by a user.The UE 10 may be fixed or mobile. The UE 10 may be referred to asanother terminology, such as a mobile station (MS), a user terminal(UT), a subscriber station (SS), a wireless device, etc.

The E-UTRAN consists of one or more base station (BS) 20. The BS 20provides the E-UTRA user plane and control plane protocol terminationstowards the UE 10. The BS 20 is generally a fixed station thatcommunicates with the UE 10. The BS 20 hosts the functions, such asinter-cell radio resource management (MME), radio bearer (RB) control,connection mobility control, radio admission control, measurementconfiguration/provision, dynamic resource allocation (scheduler), etc.The BS may be referred to as another terminology, such as an evolvedNodeB (eNB), a base transceiver system (BTS), an access point (AP), etc.

A downlink (DL) denotes communication from the BS 20 to the UE 10. Anuplink (UL) denotes communication from the UE 10 to the BS 20. Asidelink (SL) denotes communication between the UEs 10. In the DL, atransmitter may be a part of the BS 20, and a receiver may be a part ofthe UE 10. In the UL, the transmitter may be a part of the UE 10, andthe receiver may be a part of the BS 20. In the SL, the transmitter andreceiver may be a part of the UE 10.

The EPC includes a mobility management entity (MME), a serving gateway(S-GW) and a packet data network (PDN) gateway (P-GW). The MME hosts thefunctions, such as non-access stratum (NAS) security, idle statemobility handling, evolved packet system (EPS) bearer control, etc. TheS-GW hosts the functions, such as mobility anchoring, etc. The S-GW is agateway having an E-UTRAN as an endpoint. For convenience, MME/S-GW 30will be referred to herein simply as a “gateway,” but it is understoodthat this entity includes both the MME and S-GW. The P-GW hosts thefunctions, such as UE Internet protocol (IP) address allocation, packetfiltering, etc. The P-GW is a gateway having a PDN as an endpoint. TheP-GW is connected to an external network.

The UE 10 is connected to the BS 20 by means of the Uu interface. TheUEs 10 are interconnected with each other by means of the PC5 interface.The BSs 20 are interconnected with each other by means of the X2interface. The BSs 20 are also connected by means of the S1 interface tothe EPC, more specifically to the MME by means of the S1-MME interfaceand to the S-GW by means of the S1-U interface. The S1 interfacesupports a many-to-many relation between MMEs/S-GWs and BSs.

FIG. 2 shows another example of a wireless communication system to whichtechnical features of the present invention can be applied.Specifically, FIG. 2 shows a system architecture based on a 5G new radioaccess technology (NR) system. The entity used in the 5G NR system(hereinafter, simply referred to as “NR”) may absorb some or all of thefunctions of the entities introduced in FIG. 1 (e.g. eNB, MME, S-GW).The entity used in the NR system may be identified by the name “NG” fordistinction from the LTE/LTE-A.

Referring to FIG. 2, the wireless communication system includes one ormore UE 11, a next-generation RAN (NG-RAN) and a 5th generation corenetwork (5GC). The NG-RAN consists of at least one NG-RAN node. TheNG-RAN node is an entity corresponding to the BS 10 shown in FIG. 1. TheNG-RAN node consists of at least one gNB 21 and/or at least one ng-eNB22. The gNB 21 provides NR user plane and control plane protocolterminations towards the UE 11. The ng-eNB 22 provides E-UTRA user planeand control plane protocol terminations towards the UE 11.

The 5GC includes an access and mobility management function (AMF), auser plane function (UPF) and a session management function (SMF). TheAMF hosts the functions, such as NAS security, idle state mobilityhandling, etc. The AMF is an entity including the functions of theconventional MME. The UPF hosts the functions, such as mobilityanchoring, protocol data unit (PDU) handling. The UPF an entityincluding the functions of the conventional S-GW. The SMF hosts thefunctions, such as UE IP address allocation, PDU session control.

The gNBs and ng-eNBs are interconnected with each other by means of theXn interface. The gNBs and ng-eNBs are also connected by means of the NGinterfaces to the 5GC, more specifically to the AMF by means of the NG-Cinterface and to the UPF by means of the NG-U interface.

A protocol structure between network entities described above isdescribed. On the system of FIG. 1 and/or FIG. 2, layers of a radiointerface protocol between the UE and the network (e.g. NG-RAN and/orE-UTRAN) may be classified into a first layer (L1), a second layer (L2),and a third layer (L3) based on the lower three layers of the opensystem interconnection (OSI) model that is well-known in thecommunication system.

FIG. 3 shows a block diagram of a user plane protocol stack to whichtechnical features of the present invention can be applied. FIG. 4 showsa block diagram of a control plane protocol stack to which technicalfeatures of the present invention can be applied. The user/control planeprotocol stacks shown in FIG. 3 and FIG. 4 are used in NR. However,user/control plane protocol stacks shown in FIG. 3 and FIG. 4 may beused in LTE/LTE-A without loss of generality, by replacing gNB/AMF witheNB/MME.

Referring to FIG. 3 and FIG. 4, a physical (PHY) layer belonging to L1.The PHY layer offers information transfer services to media accesscontrol (MAC) sublayer and higher layers. The PHY layer offers to theMAC sublayer transport channels. Data between the MAC sublayer and thePHY layer is transferred via the transport channels. Between differentPHY layers, i.e., between a PHY layer of a transmission side and a PHYlayer of a reception side, data is transferred via the physicalchannels.

The MAC sublayer belongs to L2. The main services and functions of theMAC sublayer include mapping between logical channels and transportchannels, multiplexing/de-multiplexing of MAC service data units (SDUs)belonging to one or different logical channels into/from transportblocks (TB) delivered to/from the physical layer on transport channels,scheduling information reporting, error correction through hybridautomatic repeat request (HARQ), priority handling between UEs by meansof dynamic scheduling, priority handling between logical channels of oneUE by means of logical channel prioritization (LCP), etc. The MACsublayer offers to the radio link control (RLC) sublayer logicalchannels.

The RLC sublayer belong to L2. The RLC sublayer supports threetransmission modes, i.e. transparent mode (TM), unacknowledged mode(UM), and acknowledged mode (AM), in order to guarantee various qualityof services (QoS) required by radio bearers. The main services andfunctions of the RLC sublayer depend on the transmission mode. Forexample, the RLC sublayer provides transfer of upper layer PDUs for allthree modes, but provides error correction through ARQ for AM only. InLTE/LTE-A, the RLC sublayer provides concatenation, segmentation andreassembly of RLC SDUs (only for UM and AM data transfer) andre-segmentation of RLC data PDUs (only for AM data transfer). In NR, theRLC sublayer provides segmentation (only for AM and UM) andre-segmentation (only for AM) of RLC SDUs and reassembly of SDU (onlyfor AM and UM). That is, the NR does not support concatenation of RLCSDUs. The RLC sublayer offers to the packet data convergence protocol(PDCP) sublayer RLC channels.

The PDCP sublayer belong to L2. The main services and functions of thePDCP sublayer for the user plane include header compression anddecompression, transfer of user data, duplicate detection, PDCP PDUrouting, retransmission of PDCP SDUs, ciphering and deciphering, etc.The main services and functions of the PDCP sublayer for the controlplane include ciphering and integrity protection, transfer of controlplane data, etc.

The service data adaptation protocol (SDAP) sublayer belong to L2. TheSDAP sublayer is only defined in the user plane. The SDAP sublayer isonly defined for NR. The main services and functions of SDAP include,mapping between a QoS flow and a data radio bearer (DRB), and markingQoS flow ID (QFI) in both DL and UL packets. The SDAP sublayer offers to5GC QoS flows.

A radio resource control (RRC) layer belongs to L3. The RRC layer isonly defined in the control plane. The RRC layer controls radioresources between the UE and the network. To this end, the RRC layerexchanges RRC messages between the UE and the BS. The main services andfunctions of the RRC layer include broadcast of system informationrelated to AS and NAS, paging, establishment, maintenance and release ofan RRC connection between the UE and the network, security functionsincluding key management, establishment, configuration, maintenance andrelease of radio bearers, mobility functions, QoS management functions,UE measurement reporting and control of the reporting, NAS messagetransfer to/from NAS from/to UE.

In other words, the RRC layer controls logical channels, transportchannels, and physical channels in relation to the configuration,reconfiguration, and release of radio bearers. A radio bearer refers toa logical path provided by L1 (PHY layer) and L2 (MAC/RLC/PDCP/SDAPsublayer) for data transmission between a UE and a network. Setting theradio bearer means defining the characteristics of the radio protocollayer and the channel for providing a specific service, and setting eachspecific parameter and operation method. Radio bearer may be dividedinto signaling RB (SRB) and data RB (DRB). The SRB is used as a path fortransmitting RRC messages in the control plane, and the DRB is used as apath for transmitting user data in the user plane.

An RRC state indicates whether an RRC layer of the UE is logicallyconnected to an RRC layer of the E-UTRAN. In LTE/LTE-A, when the RRCconnection is established between the RRC layer of the UE and the RRClayer of the E-UTRAN, the UE is in the RRC connected state(RRC_CONNECTED). Otherwise, the UE is in the RRC idle state (RRC_IDLE).In NR, the RRC inactive state (RRC_INACTIVE) is additionally introduced.RRC_INACTIVE may be used for various purposes. For example, the massivemachine type communications (MMTC) UEs can be efficiently managed inRRC_INACTIVE. When a specific condition is satisfied, transition is madefrom one of the above three states to the other.

A predetermined operation may be performed according to the RRC state.In RRC_IDLE, public land mobile network (PLMN) selection, broadcast ofsystem information (SI), cell re-selection mobility, core network (CN)paging and discontinuous reception (DRX) configured by NAS may beperformed. The UE shall have been allocated an identifier (ID) whichuniquely identifies the UE in a tracking area. No RRC context stored inthe base station.

In RRC_CONNECTED, the UE has an RRC connection with the network (i.e.E-UTRAN/NG-RAN). Network-CN connection (both C/U-planes) is alsoestablished for UE. The UE AS context is stored in the network and theUE. The RAN knows the cell which the UE belongs to. The network cantransmit and/or receive data to/from UE. Network controlled mobilityincluding measurement is also performed.

Most of operations performed in RRC_IDLE may be performed inRRC_INACTIVE. But, instead of CN paging in RRC_IDLE, RAN paging isperformed in RRC_INACTIVE. In other words, in RRC_IDLE, paging formobile terminated (MT) data is initiated by core network and paging areais managed by core network. In RRC_INACTIVE, paging is initiated byNG-RAN, and RAN-based notification area (RNA) is managed by NG-RAN.Further, instead of DRX for CN paging configured by NAS in RRC_IDLE, DRXfor RAN paging is configured by NG-RAN in RRC_INACTIVE. Meanwhile, inRRC_INACTIVE, 5GC-NG-RAN connection (both C/U-planes) is established forUE, and the UE AS context is stored in NG-RAN and the UE. NG-RAN knowsthe RNA which the UE belongs to.

NAS layer is located at the top of the RRC layer. The NAS controlprotocol performs the functions, such as authentication, mobilitymanagement, security control.

The physical channels may be modulated according to OFDM processing andutilizes time and frequency as radio resources. The physical channelsconsist of a plurality of orthogonal frequency division multiplexing(OFDM) symbols in time domain and a plurality of subcarriers infrequency domain. One subframe consists of a plurality of OFDM symbolsin the time domain. A resource block is a resource allocation unit, andconsists of a plurality of OFDM symbols and a plurality of subcarriers.In addition, each subframe may use specific subcarriers of specific OFDMsymbols (e.g. first OFDM symbol) of the corresponding subframe for aphysical downlink control channel (PDCCH), i.e. L1/L2 control channel. Atransmission time interval (TTI) is a basic unit of time used by ascheduler for resource allocation. The TTI may be defined in units ofone or a plurality of slots, or may be defined in units of mini-slots.

The transport channels are classified according to how and with whatcharacteristics data are transferred over the radio interface. DLtransport channels include a broadcast channel (BCH) used fortransmitting system information, a downlink shared channel (DL-SCH) usedfor transmitting user traffic or control signals, and a paging channel(PCH) used for paging a UE. UL transport channels include an uplinkshared channel (UL-SCH) for transmitting user traffic or control signalsand a random access channel (RACH) normally used for initial access to acell.

Different kinds of data transfer services are offered by MAC sublayer.Each logical channel type is defined by what type of information istransferred. Logical channels are classified into two groups: controlchannels and traffic channels.

Control channels are used for the transfer of control plane informationonly. The control channels include a broadcast control channel (BCCH), apaging control channel (PCCH), a common control channel (CCCH) and adedicated control channel (DCCH). The BCCH is a DL channel forbroadcasting system control information. The PCCH is DL channel thattransfers paging information, system information change notifications.The CCCH is a channel for transmitting control information between UEsand network. This channel is used for UEs having no RRC connection withthe network. The DCCH is a point-to-point bi-directional channel thattransmits dedicated control information between a UE and the network.This channel is used by UEs having an RRC connection.

Traffic channels are used for the transfer of user plane informationonly. The traffic channels include a dedicated traffic channel (DTCH).The DTCH is a point-to-point channel, dedicated to one UE, for thetransfer of user information. The DTCH can exist in both UL and DL.

Regarding mapping between the logical channels and transport channels,in DL, BCCH can be mapped to BCH, BCCH can be mapped to DL-SCH, PCCH canbe mapped to PCH, CCCH can be mapped to DL-SCH, DCCH can be mapped toDL-SCH, and DTCH can be mapped to DL-SCH. In UL, CCCH can be mapped toUL-SCH, DCCH can be mapped to UL-SCH, and DTCH can be mapped to UL-SCH.

Hereinafter, estimating mobility states of a UE is described.

Besides Normal-mobility state a High-mobility and a Medium-mobilitystate are applicable if the parameters (T_(CRmax), N_(CR_H), N_(CR_M)and T_(CRmaxHyst)) are sent in the system information broadcast of theserving cell.

State detection criteria is classified into Medium-mobility statecriteria and High-mobility state criteria.

Medium-Mobility State Criteria:

-   -   If number of cell reselections during time period T_(CRmax)        exceeds N_(CR_M) and not exceeds N_(CR_H)

High-Mobility State Criteria:

-   -   If number of cell reselections during time period TCRmax exceeds        NCR_H

The UE shall not count consecutive reselections between same two cellsinto mobility state detection criteria if same cell is reselected justafter one other reselection.

State transitions are described as follow.

The UE shall:

-   -   if the criteria for High-mobility state is detected, enter        High-mobility state.    -   else if the criteria for Medium-mobility state is detected,        enter Medium-mobility state.    -   else if criteria for either Medium- or High-mobility state is        not detected during time period T_(CRmaxHyst), enter        Normal-mobility state.

If the UE is in High- or Medium-mobility state, the UE shall apply thespeed dependent scaling rules.

In order to ensure high quality of user experience in high speed train,we have already exploited dedicated resource or specific design for thecoverage of high speed railway, which is normally called“High-speed-railway dedicated LTE network”. The so-called“High-speed-railway dedicated network (HSDN)” is different from thenetwork deployed for normal ground users or low-medium mobility usersthat is normally called “public LTE network”.

FIG. 5 shows an example of overlapped coverage between dedicated networkand public network. As shown in FIG. 5, multiple radio resourceutilization (RRU) are concatenated as one single cell.

The main purpose of deploying a dedicated LTE network for high speedrailway is to provide good service for UEs on the high speed train. Thededicated LTE network is deployed either in the same frequency ordifferent frequency with the public LTE network according to thespectrum resource in that area. During the operation of dedicatednetwork, we have observed that lots of UEs which are not on the trainmay camp on and initiate service from this network, mainly due to thededicated network normally has better coverage to compensate thepenetration loss of train carriage and hence higher RSRP than the nearbypublic network from ground UE perspective, especially in those largepopulation area where there are large proportion overlapped coveragebetween dedicated network and public network, as shown in FIG. 5. So theUEs near the railway may more prefer camping on the dedicated networkwhile it is not desired from the network operation point of view, whichhas frequently caused congestion of the dedicated network. In realdeployment, we have tried several schemes to solve this problem.However, they didn't work well due to the limitation of currentspecification and implementation.

The first scheme is for inter-frequency scenario, i.e. the dedicatednetwork is deployed in a different frequency from the public network. Weset the frequency of dedicated network with higher priority to help theUE return in a short order after it dropped from the dedicated networkto public network when dedicated network is not available temporarily.However, both the UEs on the train and the UEs outside the train willhigh proportionally camp on the dedicated network.

The second scheme is as follows. In the real network, in order toprevent the UEs which are outside the train from reselecting todedicated network, the nearby public eNB does not broadcast cellreselection parameters relating to the dedicated network. Meanwhile inorder to prevent the UEs on the train from reselecting to the publicnetwork, the dedicated eNB does not broadcast cell reselectionparameters relating to the public network, however, it cannot preventUEs from camping on any network in its cell selection process.Especially, in the real network, we find out sometimes the UE on thetrain may lose coverage of the dedicated network just due to temporaryunavailability of the dedicated coverage. As the coverage of dedicatednetwork drops, UE is out of service. In this case, UE may perform cell(re)selection and probably camps on the public network. Since the publicnetwork does not broadcast cell reselection information relating toneighbour dedicated cells, the UE cannot take the cells of dedicatednetwork as candidate reselection cells. Therefore, the UE cannot quicklyreselect to the dedicated network, even if the coverage of dedicatednetwork gets better. This is contrary to our intention of deploying thededicated network.

The third scheme is introduction of load balancing based on UE speedidentification in each network respectively. Public network can handoverthe high mobility UE to dedicated network and dedicated network canhandover the low mobility UE to public network, while it will inevitablytrigger more handover procedures to load more burdens to the network andrisks to the UE experience.

Besides the experienced mechanisms discussed above, there is stillanother fundamental issue to be raised, i.e., the estimation of mobilitystate of a UE. The current mechanism for assisting estimation themobility state of a UE is simply based on serving cell change during acertain period. But in the high speed railway network, several RRUs areconcatenated in line and work as only one single cell to reduce thehandover frequency and signalling overhead, in our network, typically8˜12 RRUs are concatenated, as shown in FIG. 5. Although UE hastravelled a quite long distance in a certain period (i.e. high mobilityUEs), the UE may probably only change very few cells, which may lead thescaling factor less effective or even helpless in either cellreselection or handover process (i.e. TTT).

Based on these observations from the our real network, it is desiredthat relatively complete mechanism to be worked out to improve the LTEperformance as early as possible and such issues are to be considered inthe very initial stage of NR design.

To improve the performance, HSDN neighboring cell list may be providedin SIB.

The HSDN capable UE in high mobility state has highest priority for HSDNcell regardless of frequency priority. When UE moves to HSDN cell, theUE counts weighted value for MSE. When HSDN capable UE is not in highmobility state, the UE deprioritize the priority of HSDN to the lowestpriority.

The HSDN is proposed for high speed UE on the train. Once the UE movesto the HSDN, the UE would count amount of cell equivalent size which isbroadcasted parameter value from network and the UE would be in highmobility by MSE algorithm. So, the UE can reselect to the neighbor HSDNwith highest priority.

However, during the UE on the train stays at the train station, the UEwould not frequently reselect to other cells. So, the MSE would becomemedium or normal speed. Once UE is not in high speed, the HSDN cell islowest priority. Then, the UE would reselect to the normal cell which isnot a HSDN. It would take a time to back to HSDN because the UE speedshould be high speed again. Until UE speed comes back to the high, UEshould frequently reselect to normal cells which are not HSDN.

Moreover, if UE gets off the train and walks to out of train station, UEwould be in high speed for quite a while because UE was in HSDN cell.So, UE has highest priority for HSDN cell regardless of frequencypriority. Therefore, if UE find a HSDN cell, UE reselects to the HSDNcell until UE becomes medium or normal speed even if UE moves far fromthe HSDN cell and the signal quality of the HSDN cell is worse thannormal cells.

In conclusion, MSE enhancement should be considered for UE staying trainstation and getting off the train.

FIG. 6 shows a method for estimating mobility state of a UE according toan embodiment of the present invention.

In step S602, the UE may enter a second cell from a first cell, whereinthe first cell provides specific information. The specific informationmay inform that a cell providing the specific information ishigh-speed-railway dedicated network (HSDN) cell. The HSDN cell mayinclude plurality of public cells. The second cell may be a public cell.

In step S604, the UE may receive neighbor cell list from the secondcell.

In step S606, the UE may count a number of cell changes for mobilitystate, based on whether the neighbor cell list from the second cellincludes at least one of neighbor cells providing the specificinformation. The counting the number of cell changes for mobility statemay include: increasing the counting until that the mobility state ofthe UE is considered as high mobility state. The UE may be furtherconfigured to enter a third cell from the second cell; receive neighborcell list from the third cell; decrease the counting until that themobility state of the UE is considered as normal mobility state when theneighbor cell list from the third cell does not include the at least oneof neighbor cells providing the specific information. The counting thenumber of cell changes for mobility state may include: counting cellchange from the first cell to the second cell when the neighbor celllist from the second cell does not include the at least one of neighborcells providing the specific information.

The UE may further configured to adjust priority on the first cell as ahighest priority when the neighbor cell list includes the at least oneof neighbor cells providing the specific information. The UE may furtherconfigured to adjust priority on the first cell as a lowest prioritywhen the neighbor cell list does not include the at least one ofneighbor cells providing the specific information.

According to embodiments of the present invention, the MSE may beimproved by adjusting the number of cell reselections in considerationof various scenarios in which the UE is involved in the HDSN cell.

According to an embodiment of the present invention, cells areclassified into HSDN cell, normal cell with HSDN neighbor cell andnormal cell without HSDN neighbor cell. The HSDN cell may includeplurality of normal cells. If the UE receives HSDN neighbor cell listfrom a normal cell, the UE may consider the normal cell as the normalcell with HSDN neighbor cell. When the mobility state of the UE is highspeed, the HSDN cell may be set to highest priority for cellreselection. On the contrary, when the mobility state of the UE ismedium or normal speed, the HSDN cell may be set to lowest priority forcell reselection. When a UE is located in the HSDN cell, it may beconsidered that the UE is in high speed. In specific, when the UE islocated in the HSDN cell, the UE may increase MSE count as much as thenumber of normal cells included in the HSDN cell.

The normal cell with HSDN neighbor cell may be a neighbor cell of theHSDN cell. When the UE is located in the normal cell with HSDN neighborcell, it may be considered that the UE may move in high speed soon.

The normal cell without HSDN neighbor cell may be cell located apart bya certain distance from the HSDN cell. When the UE is located in normalcell without HSDN neighbor cell, it may be considered that the UE is innormal speed.

FIG. 7 shows a method for estimating mobility state of a UE according toan embodiment of the present invention. According to an embodiment ofthe present invention, when UE performs cell change (e.g. cellreselection or handover), UE determines UE's mobility state. The UEwhich executes following steps may be capable of HSDN operation.

In step S702, the UE may be configured to consider that a celltransmitting a HSDN indicator as a HSDN cell. In this description, theHSDN cell may be referred as a dedicated cell. The UE may be configuredto consider that a cell not transmitting a HSDN indicator as a normalcell. In this description, the normal cell may be referred as a publiccell. The HSDN indicator may be broadcasted via system information. TheUE may consider that a cell which transmits the indicator as a HSDNcell.

In step S704, when the UE performs cell change from a HSDN cell to anormal cell, UE may counts the number of cell changes based on whetherthe normal cell transmits a HSDN cell list. The HSDN cell list may be aneighbor cell list which includes a HSDN cell as a neighbor cell. TheHSDN cell may not be restricted to cells that the UE was camping on.Therefore, a normal cell which is a neighbor cell of a HSDN cell maytransmit a HSDN cell list. If the normal cell transmits HSDN cell list,the UE not in high speed may become in high speed by increasing thenumber of cell changes (e.g. by one or more counts). If the normal celldoes not transmit HSDN cell list, the UE in high speed may become inother mobility state than high speed by decreasing the number of cellchanges (e.g. by one or more counts).

In step S706, when UE performs cell change from a normal celltransmitting HSDN cell list to a normal cell not transmitting HSDN celllist, the UE in high speed may become in other mobility state than highspeed by decreasing the number of cell changes (e.g. by one or morecounts).

In step S708, the UE may determine mobility state of the UE based on thenumber of cell changes.

In step S710, if UE determines high speed as mobility state of the UE,UE may prioritize a HSDN cell or the frequency of a HSDN cell in cellreselection. The UE may consider the HSDN cell or the frequency of aHSDN cell as the highest priority in cell reselection.

In an embodiment of the present invention, the UE may adjust MSE countbased on types of the previous serving cell and the current servingcell. The types of the previous serving cell or the current serving cellmay be one of a HSDN cell, a neighbor cell with a HSDN neighbor cell, ora neighbor cell without a HSDN neighbor cell. The HSDN capable UE maytake account of not only whether the current cell is a HSDN cell butalso whether the previous cell was a HSDN cell in performing MSE. Thatis, the UE may increase or decrease MSE counting even when the currentserving cell is not the HSDN cell. The UE may check whether the currentserving cell or previous serving cell broadcasts HSDN neighbor celllist. Based on the conditions, the UE may increase or decrease the MSEcount.

In first exemplary embodiment, the HSDN capable UE was camping on HSDNcell. When the UE moves to the normal cell which broadcasts HSDNneighbor cell list (e.g. UE in the train stops at train station), the UEmay increase MSE count until UE becomes in high speed. When the UE movesto the normal cell which does not broadcast HSDN neighbor list (e.g. UEgets off train), the UE may decrease MSE count until UE would be inmedium or normal speed. The UE may decrease the MSE count as much as thenumber of normal cells included in the HSDN cell.

In second exemplary embodiment, the HSDN capable UE was camping onnormal cell which broadcasts HSDN neighbor list. When the UE moves tothe normal cell which does not broadcast HSDN neighbor list (e.g. UEgets out of train station), the UE may decrease MSE count until UE wouldbe in medium or normal speed.

FIG. 8 shows an example of estimating mobility state of an UE accordingto an embodiment of the present invention.

Referring to a first case (1) shown in FIG. 8, UE in the train may stopat train station.

The UE may get on the train and the UE may move to HSDN cell when UEbecomes high speed. Thus, the mobility state on the UE may be consideredas high speed.

Then, the UE in the train may stop at train station. The UE may not movefast during the train stops at train station. The speed of the UE may beconsidered as medium for a while. In this case, the UE may be now not inhigh speed. The UE may deprioritize the HSDN cell as lowest priority.Thus, the UE may reselect to the normal cell. The normal cell would haveHSDN neighbor cell because the normal cell is in the train station.

After UE receives the broadcasted HSDN neighbor cell list from thenormal serving cell, UE may increase MSE count until UE would be in highspeed. In this case, the UE may be regarded being high speed. Further,the UE may prioritize the HSDN cell as highest priority.

When the UE may leave the train station, the UE may be actually in highspeed. The UE may rapidly reselect to the HSDN cell as the HSDN cell isthe highest priority.

If UE does not increase MSE count when UE reselects to the normal cellwhich broadcasts HSDN neighbor cells, the UE would reselect to thenormal cell even if the train leaves the train station until UEfrequently performs reselection and UE becomes high speed.

Referring to a second case (2) shown in FIG. 8, a UE may get off thetrain.

The UE may get on the train and UE may move to HSDN cell when the UEbecomes high speed.

Then, the train may stop at train station which is final destination ofthe UE. In this case the UE may get off the train and walk through thetrain station. The UE would be in high speed for quite a while becauseUE was in the train and UE camped on HSDN cell. However, the UE wouldreselect to the normal cell when HSDN cell quality was a lot poor or UElost HSDN cell.

Then, the UE may receive neighbor cell list and if the camped servingcell does not have HSDN neighbor cell, the UE would decrease MSE countuntil UE becomes medium or normal speed. That is, the UE may just countthe cell change from the HSDN cell to a normal cell without HSDNneighbor cell.

If UE does not decrease MSE count when UE reselect to the normal cellwhich does not broadcast HSDN neighbor cells, the UE in high speed wouldkeep searching HSDN cell with highest priority. If UE finds HSDN cell,UE may reselect to the HSDN cell which cell quality is worse than normalcell because the HSDN cell is the highest priority. Even though once UElost the HSDN cell or the HSDN cell was a lot poor, the cell quality maybe changed continuously and the HSDN cell would be found after a while.However, even if UE finds the HSDN cell, the cell quality may be worsethan normal cell. Then, UE may repeat reselecting and losing the HSDNcell.

Therefore, if UE decrease the MSE count in above case, UE woulddeprioritize the HSDN cell and normally reselect to the normal cell.

Referring to a third case (3) shown in FIG. 8, a UE may get out of trainstation.

The UE may get on the train and UE moves to HSDN cell when UE becomeshigh speed. The train may stop at train station. The UE may get off thetrain and walks through the train station. The UE would be in high speedfor quite a while because UE was in the train and UE camped on HSDNcell. However, UE would reselect to the normal cell when HSDN cellquality was temporarily a lot poor or UE temporarily lost HSDN cell.

Then, the UE may receive neighbor cell list and if the camped servingcell has HSDN neighbor, the UE would keep MSE count high speed as thefirst case (1). The UE may go back to the train, so the UE may keep MSEcount high.

The UE may reselect to the normal cell. The UE may receive neighbor celllist and if the camped serving cell does not have HSDN neighbor cell,the UE may decrease MSE count until UE becomes medium or normal speed.

If UE reselects to the normal cell and the cell has HSDN neighbor celllist, the cell would be near the HSDN cell. Then, UE may need to keephigh speed because UE may go back to the train. After UE moves to thenormal cell and the normal cell does not have HSDN neighbor cell list,the normal cell would not be near the HSDN cell. Then, UE may need todecrease MSE count.

According to an embodiment of the present invention, state transitionsfor HSDN capable UE may be performed as follow.

State Detection Criteria:

Medium-Mobility State Criteria:

-   -   If number of cell reselections during time period TCRmax exceeds        NCR_M and not exceeds NCR_H

High-Mobility State Criteria:

-   -   If number of cell reselections during time period TCRmax exceeds        NCR_H

The UE shall not count consecutive reselections between same two cellsinto mobility state detection criteria if same cell is reselected justafter one other reselection.

Regard to State transitions, the UE shall:

-   -   if the criteria for High-mobility state is detected:    -   enter High-mobility state.    -   else if the criteria for Medium-mobility state is detected:    -   enter Medium-mobility state.    -   else if criteria for either Medium- or High-mobility state is        not detected during time period TCRmaxHyst:    -   enter Normal-mobility state.

If the UE is in High- or Medium-mobility state, the UE shall apply thespeed dependent scaling rules.

The HSDN capable UE shall:

If UE is not in High-mobility state and the previous serving cell wasHSDN cell:

-   -   If the current serving cell is not HSDN and broadcasts HSDN in        neighbour cell list:    -   Increase the number of cell reselections until the number of        cell reselections exceeds NCR_H

If UE is in High-mobility state and the previous serving cell was HSDNcell:

-   -   If the current serving cell is not HSDN and does not broadcasts        HSDN in neighbour cell list:    -   Decrease the number of cell reselections until the number of        cell reselections becomes below NCR_H

If UE is in High-mobility state and the previous serving cell was notHSDN cell but broadcasted HSDN in neighbour list:

-   -   If the current serving cell is not HSDN and does not broadcasts        HSDN in neighbour cell list:    -   Decrease the number of cell reselections until the number of        cell reselections becomes below NCR_H

FIG. 9 shows a UE to implement an embodiment of the present invention.The present invention described above for UE side may be applied to thisembodiment.

A UE 600 includes a processor 610, a memory 620 and a transceiver 630.The processor 610 may be configured to implement proposed functions,procedures and/or methods described in this description. Layers of theradio interface protocol may be implemented in the processor 610.

Specifically, the processor 610 is configured to enter a second cellfrom a first cell, wherein the first cell provides specific information.The specific information may inform that a cell providing the specificinformation is high-speed-railway dedicated network (HSDN) cell. TheHSDN cell may include plurality of public cells. The second cell may bea public cell.

The processor 610 is configured to receive neighbor cell list from thesecond cell.

The processor 610 is configured to count a number of cell changes formobility state, based on whether the neighbor cell list from the secondcell includes at least one of neighbor cells providing the specificinformation. The counting the number of cell changes for mobility statemay include: increasing the counting until that the mobility state ofthe UE is considered as high mobility state. The processor 610 isfurther configured to enter a third cell from the second cell; receiveneighbor cell list from the third cell; decrease the counting until thatthe mobility state of the UE is considered as normal mobility state whenthe neighbor cell list from the third cell does not include the at leastone of neighbor cells providing the specific information. The countingthe number of cell changes for mobility state may include: counting cellchange from the first cell to the second cell when the neighbor celllist from the second cell does not include the at least one of neighborcells providing the specific information.

The processor 610 is configured to adjust priority on the first cell asa highest priority when the neighbor cell list includes the at least oneof neighbor cells providing the specific information. The UE may furtherconfigured to adjust priority on the first cell as a lowest prioritywhen the neighbor cell list does not include the at least one ofneighbor cells providing the specific information.

The memory 620 is operatively coupled with the processor 610 and storesa variety of information to operate the processor 610. The transceiver630 is operatively coupled with the processor 610, and transmits and/orreceives a radio signal.

The processor 610 may include application-specific integrated circuit(ASIC), other chipset, logic circuit and/or data processing device. Thememory 620 may include read-only memory (ROM), random access memory(RAM), flash memory, memory card, storage medium and/or other storagedevice. The transceiver 630 may include baseband circuitry to processradio frequency signals. When the embodiments are implemented insoftware, the techniques described herein can be implemented withmodules (e.g., procedures, functions, and so on) that perform thefunctions described herein. The modules can be stored in the memory 620and executed by the processor 610. The memory 620 can be implementedwithin the processor 610 or external to the processor 610 in which casethose can be communicatively coupled to the processor 610 via variousmeans as is known in the art.

According to embodiment of the present invention shown in FIG. 9, theMSE may be improved by adjusting the number of cell reselections inconsideration of various scenarios in which the UE is involved in theHDSN cell.

FIG. 10 shows more detailed UE to implement an embodiment of the presentinvention. The present invention described above for UE side may beapplied to this embodiment.

A UE includes a processor 610, a power management module 611, a battery612, a display 613, a keypad 614, a subscriber identification module(SIM) card 615, a memory 620, a transceiver 630, one or more antennas631, a speaker 640, and a microphone 641.

The processor 610 may be configured to implement proposed functions,procedures and/or methods described in this description. Layers of theradio interface protocol may be implemented in the processor 610. Theprocessor 610 may include ASIC, other chipset, logic circuit and/or dataprocessing device. The processor 610 may be an application processor(AP). The processor 610 may include at least one of a digital signalprocessor (DSP), a central processing unit (CPU), a graphics processingunit (GPU), a modem (modulator and demodulator). An example of theprocessor 610 may be found in SNAPDRAGON™ series of processors made byQualcomm®, EXYNOS™ series of processors made by Samsung®, a series ofprocessors made by Apple®, HELIO™ series of processors made byMediaTek®, ATOM™ series of processors made by Intel® or a correspondingnext generation processor.

The processor 610 is configured to enter a second cell from a firstcell, wherein the first cell provides specific information. The specificinformation may inform that a cell providing the specific information ishigh-speed-railway dedicated network (HSDN) cell. The HSDN cell mayinclude plurality of public cells. The second cell may be a public cell.

The processor 610 is configured to receive neighbor cell list from thesecond cell.

The processor 610 is configured to count a number of cell changes formobility state, based on whether the neighbor cell list from the secondcell includes at least one of neighbor cells providing the specificinformation. The counting the number of cell changes for mobility statemay include: increasing the counting until that the mobility state ofthe UE is considered as high mobility state. The processor 610 isfurther configured to enter a third cell from the second cell; receiveneighbor cell list from the third cell; decrease the counting until thatthe mobility state of the UE is considered as normal mobility state whenthe neighbor cell list from the third cell does not include the at leastone of neighbor cells providing the specific information. The countingthe number of cell changes for mobility state may include: counting cellchange from the first cell to the second cell when the neighbor celllist from the second cell does not include the at least one of neighborcells providing the specific information.

The processor 610 is configured to adjust priority on the first cell asa highest priority when the neighbor cell list includes the at least oneof neighbor cells providing the specific information. The UE may furtherconfigured to adjust priority on the first cell as a lowest prioritywhen the neighbor cell list does not include the at least one ofneighbor cells providing the specific information.

The power management module 611 manages power for the processor 610and/or the transceiver 630. The battery 612 supplies power to the powermanagement module 611. The display 613 outputs results processed by theprocessor 610. The keypad 614 receives inputs to be used by theprocessor 610. The keypad 614 may be shown on the display 613. The SIMcard 615 is an integrated circuit that is intended to securely store theinternational mobile subscriber identity (IMSI) number and its relatedkey, which are used to identify and authenticate subscribers on mobiletelephony devices (such as mobile phones and computers). It is alsopossible to store contact information on many SIM cards.

The memory 620 is operatively coupled with the processor 610 and storesa variety of information to operate the processor 610. The memory 620may include ROM, RAM, flash memory, memory card, storage medium and/orother storage device. When the embodiments are implemented in software,the techniques described herein can be implemented with modules (e.g.,procedures, functions, and so on) that perform the functions describedherein. The modules can be stored in the memory 620 and executed by theprocessor 610. The memory 620 can be implemented within the processor610 or external to the processor 610 in which case those can becommunicatively coupled to the processor 610 via various means as isknown in the art.

The transceiver 630 is operatively coupled with the processor 610, andtransmits and/or receives a radio signal. The transceiver 630 includes atransmitter and a receiver. The transceiver 630 may include basebandcircuitry to process radio frequency signals. The transceiver 630controls the one or more antennas 631 to transmit and/or receive a radiosignal.

The speaker 640 outputs sound-related results processed by the processor610. The microphone 641 receives sound-related inputs to be used by theprocessor 610.

According to embodiment of the present invention shown in FIG. 10, theMSE may be improved by adjusting the number of cell reselections inconsideration of various scenarios in which the UE is involved in theHDSN cell.

In this document, the term “/” and “,” should be interpreted to indicate“and/or.” For instance, the expression “A/B” may mean “A and/or B.”Further, “A, B” may mean “A and/or B.” Further, “A/B/C” may mean “atleast one of A, B, and/or C.” Also, “A, B, C” may mean “at least one ofA, B, and/or C.”

Further, in the document, the term “or” should be interpreted toindicate “and/or.” For instance, the expression “A or B” may comprise 1)only A, 2) only B, and/or 3) both A and B. In other words, the term “or”in this document should be interpreted to indicate “additionally oralternatively.”

In view of the exemplary systems described herein, methodologies thatmay be implemented in accordance with the disclosed subject matter havebeen described with reference to several flow diagrams. While forpurposed of simplicity, the methodologies are shown and described as aseries of steps or blocks, it is to be understood and appreciated thatthe claimed subject matter is not limited by the order of the steps orblocks, as some steps may occur in different orders or concurrently withother steps from what is depicted and described herein. Moreover, oneskilled in the art would understand that the steps illustrated in theflow diagram are not exclusive and other steps may be included or one ormore of the steps in the example flow diagram may be deleted withoutaffecting the scope and spirit of the present disclosure.

What has been described above includes examples of the various aspects.It is, of course, not possible to describe every conceivable combinationof components or methodologies for purposes of describing the variousaspects, but one of ordinary skill in the art may recognize that manyfurther combinations and permutations are possible. Accordingly, thesubject specification is intended to embrace all such alternations,modifications and variations that fall within the scope of the appendedclaims.

What is claimed is:
 1. A method for a wireless device in wirelesscommunication system, the method comprising: entering a second cell froma first cell, wherein the first cell provides specific information;receiving neighbor cell list from the second cell; and counting a numberof cell changes for mobility state, wherein the number of cell changesis increased, until the mobility state of the wireless device isconsidered a high mobility state, based on the neighbor cell list fromthe second cell including at least one of neighbor cells providing thespecific information.
 2. The method of claim 1, wherein the specificinformation informs that a cell providing the specific information ishigh-speed-railway dedicated network (HSDN) cell.
 3. The method of claim2, wherein the HSDN cell includes plurality of public cells.
 4. Themethod of claim 1, wherein the second cell is a public cell.
 5. Themethod of claim 1, further comprising: entering a third cell from thesecond cell; receiving neighbor cell list from the third cell;decreasing the number of cell changes, until the mobility state of thewireless device is considered as normal mobility state, based on theneighbor cell list from the third cell not including the at least one ofneighbor cells providing the specific information.
 6. The method ofclaim 1, further comprising: adjusting priority on the first cell as ahighest priority based on the neighbor cell list including the at leastone of neighbor cells providing the specific information.
 7. The methodof claim 1, further comprising: adjusting priority on the first cell asa lowest priority based on the neighbor cell list not including the atleast one of neighbor cells providing the specific information.
 8. Awireless device in a wireless communication system, the wireless devicecomprising: a transceiver for transmitting or receiving a radio signal;and a processor coupled to the transceiver, the processor configured to:enter a second cell from a first cell, wherein the first cell providesspecific information; receive neighbor cell list from the second cell;and count a number of cell changes for mobility state, wherein thenumber of cell changes is increased, until the mobility state of thewireless device is considered a high mobility state, based on theneighbor cell list from the second cell including at least one ofneighbor cells providing the specific information.
 9. The wirelessdevice of claim 8, wherein the specific information informing that acell providing the specific information is high-speed-railway dedicatednetwork (HSDN) cell.
 10. The wireless device of claim 9, wherein theHSDN cell includes plurality of public cells.
 11. The wireless device ofclaim 8, wherein the second cell is a public cell.
 12. A processor for awireless communication device in a wireless communication system,wherein the processor is configured to control the wirelesscommunication device to: enter a second cell from a first cell, whereinthe first cell provides specific information; receive neighbor cell listfrom the second cell; and count a number of cell changes for mobilitystate, wherein the number of cell changes is increased, until themobility state of the wireless device is considered a high mobilitystate, based on the neighbor cell list from the second cell including atleast one of neighbor cells providing the specific information.